140 lines · plain
1.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later2.. c:namespace:: V4L3 4.. _VIDIOC_ENUM_FREQ_BANDS:5 6****************************7ioctl VIDIOC_ENUM_FREQ_BANDS8****************************9 10Name11====12 13VIDIOC_ENUM_FREQ_BANDS - Enumerate supported frequency bands14 15Synopsis16========17 18.. c:macro:: VIDIOC_ENUM_FREQ_BANDS19 20``int ioctl(int fd, VIDIOC_ENUM_FREQ_BANDS, struct v4l2_frequency_band *argp)``21 22Arguments23=========24 25``fd``26 File descriptor returned by :c:func:`open()`.27 28``argp``29 Pointer to struct :c:type:`v4l2_frequency_band`.30 31Description32===========33 34Enumerates the frequency bands that a tuner or modulator supports. To do35this applications initialize the ``tuner``, ``type`` and ``index``36fields, and zero out the ``reserved`` array of a struct37:c:type:`v4l2_frequency_band` and call the38:ref:`VIDIOC_ENUM_FREQ_BANDS` ioctl with a pointer to this structure.39 40This ioctl is supported if the ``V4L2_TUNER_CAP_FREQ_BANDS`` capability41of the corresponding tuner/modulator is set.42 43.. tabularcolumns:: |p{2.9cm}|p{2.9cm}|p{5.8cm}|p{2.9cm}|p{2.4cm}|44 45.. c:type:: v4l2_frequency_band46 47.. flat-table:: struct v4l2_frequency_band48 :header-rows: 049 :stub-columns: 050 :widths: 1 1 2 1 151 52 * - __u3253 - ``tuner``54 - The tuner or modulator index number. This is the same value as in55 the struct :c:type:`v4l2_input` ``tuner`` field and56 the struct :c:type:`v4l2_tuner` ``index`` field, or57 the struct :c:type:`v4l2_output` ``modulator`` field58 and the struct :c:type:`v4l2_modulator` ``index``59 field.60 * - __u3261 - ``type``62 - The tuner type. This is the same value as in the struct63 :c:type:`v4l2_tuner` ``type`` field. The type must be64 set to ``V4L2_TUNER_RADIO`` for ``/dev/radioX`` device nodes, and65 to ``V4L2_TUNER_ANALOG_TV`` for all others. Set this field to66 ``V4L2_TUNER_RADIO`` for modulators (currently only radio67 modulators are supported). See :c:type:`v4l2_tuner_type`68 * - __u3269 - ``index``70 - Identifies the frequency band, set by the application.71 * - __u3272 - ``capability``73 - :cspan:`2` The tuner/modulator capability flags for this74 frequency band, see :ref:`tuner-capability`. The75 ``V4L2_TUNER_CAP_LOW`` or ``V4L2_TUNER_CAP_1HZ`` capability must76 be the same for all frequency bands of the selected77 tuner/modulator. So either all bands have that capability set, or78 none of them have that capability.79 * - __u3280 - ``rangelow``81 - :cspan:`2` The lowest tunable frequency in units of 62.5 kHz, or82 if the ``capability`` flag ``V4L2_TUNER_CAP_LOW`` is set, in units83 of 62.5 Hz, for this frequency band. A 1 Hz unit is used when the84 ``capability`` flag ``V4L2_TUNER_CAP_1HZ`` is set.85 * - __u3286 - ``rangehigh``87 - :cspan:`2` The highest tunable frequency in units of 62.5 kHz,88 or if the ``capability`` flag ``V4L2_TUNER_CAP_LOW`` is set, in89 units of 62.5 Hz, for this frequency band. A 1 Hz unit is used90 when the ``capability`` flag ``V4L2_TUNER_CAP_1HZ`` is set.91 * - __u3292 - ``modulation``93 - :cspan:`2` The supported modulation systems of this frequency94 band. See :ref:`band-modulation`.95 96 .. note::97 98 Currently only one modulation system per frequency band99 is supported. More work will need to be done if multiple100 modulation systems are possible. Contact the linux-media101 mailing list102 (`https://linuxtv.org/lists.php <https://linuxtv.org/lists.php>`__)103 if you need such functionality.104 * - __u32105 - ``reserved``\ [9]106 - Reserved for future extensions.107 108 Applications and drivers must set the array to zero.109 110 111.. tabularcolumns:: |p{6.6cm}|p{2.2cm}|p{8.5cm}|112 113.. _band-modulation:114 115.. flat-table:: Band Modulation Systems116 :header-rows: 0117 :stub-columns: 0118 :widths: 3 1 4119 120 * - ``V4L2_BAND_MODULATION_VSB``121 - 0x02122 - Vestigial Sideband modulation, used for analog TV.123 * - ``V4L2_BAND_MODULATION_FM``124 - 0x04125 - Frequency Modulation, commonly used for analog radio.126 * - ``V4L2_BAND_MODULATION_AM``127 - 0x08128 - Amplitude Modulation, commonly used for analog radio.129 130Return Value131============132 133On success 0 is returned, on error -1 and the ``errno`` variable is set134appropriately. The generic error codes are described at the135:ref:`Generic Error Codes <gen-errors>` chapter.136 137EINVAL138 The ``tuner`` or ``index`` is out of bounds or the ``type`` field is139 wrong.140